6.25 pm: Pakistan Election Commission extends time for voting by an hour following large voter turnout across the country in the landmark elections. The voting was set to end at 5 pm (local time, 5.30 IST) but sizable number of voters kept arriving at the polling stations.

In some constituencies in Karachi, polling has been extended till 7 pm (7:30 IST) as voters faced problems earlier in the day. Election officials said that turn out was expected to be 60 per cent.

6.14 pm: Pakistan's Election Commission said on Saturday it failed to hold free and fair elections in the country's commercial centre and biggest city, Karachi. "We have been unable to carry out free and fair elections in Karachi," it said in a statement. It is unclear whether the commission's conclusion means national elections will have to be held again.

5.55 pm: Malala Yousufzai, teenage rights activist who was shot in the head by the Taliban, on Saturday appealed to people to exercise their franchise, saying "one vote can change" Pakistan's future. "It's an honour for me to share some words with my sisters and brothers in my country," Malala said in a letter carried by the Dawn newspaper.

5.50 pm: Dawn reported that the Election Commission of Pakistan has warned that if the rumours of vote rigging, in Karachi and Hyderabad, are found to be true, the results would be annulled. The Jamaat-i-Islami on Saturday announced it would boycott the polls as the votes were rigged.

5.20 pm: Former prime minister and head of his faction of Pakistan Muslim League-Nawaz, Nawaz Sharif, casts his vote in the eastern city of Lahore. The PML-N is widely expected to win these elections.

2.05 pm: Thirty per cent polling recorded till 2.00 pm.

2:00 pm: The number of people injured in twin blasts in Pakistan on election day rises to 50. At least ten people were killed and 50 others injured in twin explosions outside the Awami National Party office in Karachi's Quaidabad area. A blast also took place near a school in Peshawar injuring 12 people. The school is a designated polling station.

1:20 pm: Some of the injured were in critical condition, said sources with Jinnah Hospital where the wounded were taken.

13:01 pm: The huge explosion damaged the windowpanes of several buildings and destroyed eight shops in Quaidabad, Karachi.

12:26 pm: Polling in Pakistan's landmark general election was marred by four bomb blasts in Karachi, Quetta and Peshawar that killed at least 10 people and injured over 40.

11:52 am: Death toll rises to 10 in Karachi blast.

11:16 am: No group has claimed responsibility for the attack though the banned Tehrik-e-Taliban Pakistan has repeatedly targeted the ANP and other secular-leaning parties like the Pakistan Peoples Party and Muttahida Qaumi Movement during the campaign period.

11:00 am: Five persons were killed and 15 others injured after a bomb went off near a secular political party's election office. State-run Radio Pakistan reports that five persons were killed and 15 injured by the explosion.

10:56 am: PTI reports five killed in a blast near Awami National Party (ANP) election office in Karachi, Pakistan.

Security tightened in Pakistan as polling began on Saturday amidst threats of violence and terror. A total of 85 million people are expected to cast their votes for 342 national assembly seats with approximately 40 million of them being first time voters. The ruling PPP is widely expected to be defeated with the PMLN and the PTI being seen as the major gainers.

Saturday's polls follow the bloodiest election campaign in recent Pakistani history. It will also mark a democratic change of power from one civilian government to another after decades of army rule that ended five years ago. Pakistanis will be casting two votes on Saturday - one for the National Assembly constituency and another for their Provincial Assembly constituency.

Long queues of people were seen outside polling stations well before the start of polling. Tight security arrangements have been made across the country to ensure peaceful, free and transparent elections. The 63-year-old Nawaz Sharif-led PML-N is widely tipped to emerge as the single largest party in the polls. He could end up becoming a premier for the third time if he is able to cobble together a coalition comprising the religious, nationalist and right wing parties that are expected to do well in the provinces.

A spirited campaign over the past few weeks by cricketer-turned-politician Imran Khan, 60, has boosted the chances of his Pakistan Tehrik-e-Insaf party, particularly in Punjab province which has 147 - or more than half - of the 272 parliamentary seats for which polls will be held.

Some experts point out that Khan, who is hospitalised after having fallen down from a forklift during campaign, could gain some sympathy votes. The National Assembly or lower house of parliament has a total of 342 seats and the rest will be allocated to women and minority candidates nominated by parties.

Over 86 million people are registered to vote but elections in Pakistan have traditionally registered low turnouts. A total of 4,670 candidates are standing for parliamentary elections while nearly 11,000 are running for the four provincial assemblies.

Parties like the Pakistan Tehrik-e-Insaf, Pakistan Peoples Party and PML-N have sought to attract many youths who will be voting for the first time. The PML-N and Khan's party were the only major political forces that were able to conduct a nationwide campaign after the banned Tehrik-e-Taliban Pakistan warned that it would target leaders and rallies of the secular-leaning PPP, Awami National Party and Muttahida Qaumi Movement, which were part of the outgoing coalition.

This would be the first time in Pakistan's history that a democratic transition of power would take place. The previous PPP-led government had for the first time completed its five year term in the country that has seen numerous military coups.